Case IH 328 – Engine Controller (ENG): Rear Pumping element is failed

This fault code indicates a failure associated with the rear pumping element of the Cummins Accumulator Pump System (CAPS) fuel injection pump. The CAPS pump utilizes an accumulator/pumping plunger module with two pumping control valves. While the code points to a mechanical failure of the rear pumping element itself, it is frequently triggered by severe fuel starvation or air entering the system.

• MX Magnum
• STX Steiger
• MX240
• MX255
• MX270
• MX285
• STX275
• STX325
• Steiger 275
• Steiger 325
• Axial-Flow 2388
• 2577
• 2588
• SPX4410
• FLX3300B
• FLX3510
• FLX4010
• FLX4300
• FLX4375
• FLX4510
• CPX610
• CPX620
• TG210
• TG230
• TG255
• TG285
• TJ275
• TJ325

1. 1

   Check Fuel Filters: Inspect and replace the fuel filters to ensure there is no restricted fuel flow.

2. 2

   Inspect for Air Ingress: Check for air entering the system anywhere between the fuel tank and the CAPS pump.

3. 3

   Inspect Fuel Lines: Check the fuel hoses for kinking (especially at the tank outlet) or degradation. A common issue on these tractors is a hydraulic leak under the cab soaking the fuel hoses, causing them to become "mushy" and collapse under suction.

1. 1

   Resolve Fuel Supply Issues

   If the diagnostic checks reveal collapsed lines, clogged filters, or air leaks, repair these first, clear the codes, and test the machine under load.

2. 2

   Replace the CAPS Pump

   If fuel supply is verified and Code 328 persists, the rear pumping element has suffered an actual mechanical failure. The CAPS injection pump cannot typically be repaired in the field and must be replaced with a remanufactured unit.

3. 3

   Replace the Transient Suppressor

   When installing a remanufactured CAPS pump, it is highly recommended (and required by most remanufacturers for warranty validation) to replace the Cummins Transient Suppressor at the same time.

4. 4

   Alternative (P-Pump Conversion)

   Due to the high failure rate and cost of CAPS pumps, many owners opt to install a CAPS-to-Inline P7100 mechanical injection pump conversion kit. (Note: Conversion kits may not be compatible with certain powershift transmissions on articulating tractors like the STX275/325).